Secret telegraph-sounder.



= an electromagnet O in the other end.

'UNITED STATES PATENT OFFICE.

GEORGE H. LANDGRAF, O-F WATERLOO, \VISCONSIN.

, SECRET TELEGRAPH-'SOUNDER.

SPECIFICATION forming part of Letters Patent No. 654,834, dated July 31 1900. Application filed June 21, 1898. Serial No. 684,05A. (No model.)

To all whom it may concern.- 7

Be it known that I, GEORGE H. LANDGRAF, a citizen of the Un ted States, residing at Waterloo, in the county. of Jefferson and State of Wisconsin, have invented new and useful Improvements in Secret Telegraph- Sounders, of which the following is a specification.

My invention relates to improvementsin secret telegraph-sounders.

The objects-of my invention are, first, to provide. a portable telegraphic receiving instrument of miniature proportions which-may be suspended from the ear. or teeth of the operator and .is adapted to produce telegraphic signals audible only to the operator, and, second, to provide forthe interchangeable use of my device with a receiver or sounder of ordinary construction.

In the following description reference is had tot-he accompanying drawings,in which Figure 1 is a central longitudinal section view of my improved sounder, showing the electromagnet and armature therein. Fig. 2 is a plan view illustrating the connections adapted to permitthe use of my device interchangeably with the ordinary telegraphic receiver or sounder.

Like parts are identified by the same reference-letters in both views.

Referring to the drawings, A is a tubular casing or inclosure provided with a longitudinally-vibrating armature B in one end and The armature is preferably located in a cylinder 1), of brass or other non-magnetic material, in the lower end of which the core E of the electromagnet G is screwed, the armature being held normally out of contact with the magnet by means of a spring F. The upper end of the cylinder D is closed by a removable end piece G, provided with a centrallydisposed aperture in which the upper end of the armature is entered. H is an adj usting-screw fitting in said aperture and adapted. to regulate the length of stroke of the armature.-

armature either by means of -the vibration of the material itself or the air in a duct 1-, with which the piece is preferably provided. The lower end of the casing is closed by an end 'piece J,.which is provided with an aperture K, through which the electrical conductors L L are passed to the magnet O. A convenient mode of construction is shown in Fig. l, in which the core E is provided with a screw-threaded enlargement E, adapted to engage interiorly screw threaded portions a and j of the casing A and J, respectively, whereby the parts E, A, and J are secured together. In this construction the part E is also provided with apertures e, through whichthe electrical cond uctors L and L pass.

Referring now to Fig. 2, in which I show my invention arranged to be used interchangeably with the ordinary telegraph-sounder, itwiII-be observed that I have provided a switchboard M, having a switch-lever N,0perating upon two switch-points n and a. The

switch-lever is connected to one pole of the battery-circuit by the conductor 0 and when brought into contact with the switch-point n R, and S; but when the lever Nis brought in contact with the switch-poi'ntn the circuit is completed through my improved sounder by means of conductors O, L, L, S, and S.

terchangeably a variety of means may be em-- ployed to permit such use not involving the use of an independent switchboard. I prefer to use the latter, however, as Ican thereby apply my invention to any-of the ordinary sounders now in use without disturbing or disarranging the latter.

From the foregoing description it will be understood that my improved sounder is adapted to be applied to the ear of the operator, the tip I" of the earpiece I'being adapted to be engaged between the lobes of the ear completes the circuit through an ordinary sounder P by means of the conductors O, Q,

IOQ

and the sounder held in a suspended position v thereby. It may also be suspended by a spring or elastic cord U from the ceiling or any other direct contact with the instrument, but will be distinctly heard when the piece, I is applied to the car. It will also be heard or felt in case the piece I is taken between the teeth, and by this means a deaf person may receive telegraphic messages.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-- '1. A secret telegraph-sounder, comprising an inclosing tubular case provided with nonmagnetic armatu re-bushings; an electromagnet having its core engaged in one of said bushings; a longitudinally-vibratory rod engaged in said bushings and adapted to 'contact with the end of the magnet-core; a spring coiled about said armature and adapted to support the saine normally out of con tact with the magnet-core; a removable cap for one end of said inclosin g case extending in the form of a curved earpiece, and flexible conductors included in a telegraphic circuit and connected with said magnet through the other end of said case;

2. A secret telegraph-sounder, comprising 'an electro'mag'net, included in a telegraphic circuit by flexible conductors; an armature inclosing cylinder closed at both ends by apertured caps or bushings; a longitudinallyvibratory armature having its ends engaged in said bushings and adapted to contact with the magnet-core; an adjusting-screw adapted to enter one of said end caps or bushings to limit the movement of the armature; an inclosing tubular case covering said magnet and armatnre-cylinder, and provided with a removable end cap extendingto form a curved earpiece adapted to be engaged in the ear of the operator and support the entire device th e refro m.

3. A secret telegraph-sounder comprising for the purpose set forth.

In testimony whereof I have hereunto set my hand this 13th day of June, 1898.

GEORGE H. LANDGRAF.

Witnesses:

L. S. HURD, T. A. WILLIAMS. 

